CONCEPT BLOGS
Multi-phase guides with mental models, worked examples, diagrams, and real edge cases — the public form of Learnisim AI's conceptual learning. Read here; train it interactively in the app.
Learn how to find where a linked list cycle begins. Trace the entrance of 1→2→3→4→5→3 step by step using Floyd's Tortoise and Hare.
Learn linked list cycle detection (Floyd) by tracing the tortoise and hare on a cyclic 1→2→3→4→5→3 list versus an acyclic 1→2→3→null list.
![Duplicate in [1, 3, 4, 2, 2] via Floyd overview diagram](/blogs/find-the-duplicate-number-explained-tracing-1-3-4-2-2-via-floyds-cycle/diagrams/hero.svg)
Learn how to find duplicate numbers in O(n) time and O(1) space by treating array values as pointers. Trace the cycle in [1, 3, 4, 2, 2] step by step.
